1. Field of the Invention
The present invention pertains to apparatus and methods for fastening two or more objects together. In particular, it concerns apparatus and methods for fastening such objects together with fastener devices having shafts and cooperating members for holding the shafts in tension, i.e. bolts, studs and the like.
2. Description of the Prior Art
One of the problems associated with connecting objects together, such as flange-type connections, is the assurance that the connection is properly made up by placing the desired tension on the flange bolts or studs. Due to the friction involved with tightening a nut, it is difficult to assure that proper and equal tension is applied to all of the bolts or studs of the connection. Furthermore, it is physically difficult to apply the proper tension with an ordinary wrench. Even a torque wrench may not ensure proper and equal application of tension to the bolts and studs of the connections.
To overcome some of the problems associated with ordinary wrench and torque wrench application of tension, various bolt or stud tensioning apparatus have been developed. Examples of such apparatus may be seen in U.S. Pat. Nos. 2,866,370; 3,015,975; 3,158,052; 3,230,799; and 3,749,362. There are several problems associated with such stuc or bolt stretchers or tensioners. For one, they are relatively expensive to manufacture and use. To assure equal application of tension may require several pieces of equipment.
Since the bolt and stud tensioning apparatus of the prior art are expensive, they are naturally designed for reuse. As a result, most, if not all, of the bolt and stud tensioners of the prior art require attachment to the end of the stud for application of the tensioning force. This means that tension must be applied with the stud nut already engaged with the stud and that some means must be provided for internal access to the tensioning unit to tighten the stud nut upon application of the desired tensioning force. Although various mechanical devices have been developed to improve this feature, they make the unit more expensive, complex and difficult to apply.